Quantum Hall effect on top and bottom surface states of topological insulator (Bi1−xSbx)2Te3 filmsQuantum Hall effect on top and bottom surface states of topological insulator (Bi1−xSbx)2Te3 filmsAA12645905

UTokyo Research掲載「トポロジカル絶縁体の表面ディラック状態の量子化を実証」 URI: http://www.u-tokyo.ac.jp/ja/utokyo-research/research-news/observation-of-quantization-in-surface-dirac-states-of-topological-insulator.htmlUTokyo Research "Observation of quantization in surface Dirac states of topological insulator" URI: http://www.u-tokyo.ac.jp/en/utokyo-research/research-news/observation-of-quantization-in-surface-dirac-states-of-topological-insulator.htmlThe three-dimensional topological insulator is a novel state of matter characterized by two-dimensional metallic Dirac states on its surface. To verify the topological nature of the surface states, Bi-based chalcogenides such as Bi2Se3, Bi2Te3, Sb2Te3 and their combined/mixed compounds have been intensively studied. Here, we report the realization of the quantum Hall effect on the surface Dirac states in (Bi1−xSbx)2Te3 films. With electrostatic gate-tuning of the Fermi level in the bulk band gap under magnetic fields, the quantum Hall states with filling factor ±1 are resolved. Furthermore, the appearance of a quantum Hall plateau at filling factor zero reflects a pseudo-spin Hall insulator state when the Fermi level is tuned in between the energy levels of the non-degenerate top and bottom surface Dirac points. The observation of the quantum Hall effect in three-dimensional topological insulator films may pave a way toward topological insulator-based electronics.